| Ramie bast fiber is a kind of natural fiber, which sales well to the world as a kind of high-class textile material. Because ramie bast fiber includes much degum and can not be used as textile material, degumming of ramie bast fiber is a key process. At present, chemical treatment is a common method of the degumming of ramie bast fiber. But it consists in many unconquerable defaults, so biological degumming is tend to replace chemical degumming in recent years.The performance of producing enzymes of mixed strains in nature was studied. Three fine strains (A1, A2, A3) were selected from the mixed system and the activity of enzymes produced by them were measured.The medium used to produce enzyme was determined and the enzyme-producing curve was protracted. The conditions of ferment of these strains and the conditions of degumming technics of these strains were optimiz-ed. Finally the ramie bast fiber was degummed by two kinds of the strains.①The performance of producing enzymes of mixed strains in natureIn the process of static degumming, the mixed strains produced pectinase mainly which decomposed pectin at first, then the activity of xylanase and mannanase increased which decomposed hemicellulose faster. In the process of oscillatory degumming, pec-tinase, xylanase and produced in-phase and the cooperation effect of the three kinds of enzymes was fine, so the rate of degumming was fast and gained good results in the process of the degumming.②The selectness of the degumming strains and the ferment conditions of the degumming strainsThree fine degumming strains of fungi were selected, the rate of the degumming reached 24%, 23.28%, 15.36% respectively. By comparing the activity of enzymes produced by the selected degumming strains and the effect of the degumming, it proved that if the kinds of the enzymes were more complete and the stability of the enzymes was higher, the result of the degumming was better.The optimum ferment conditions of the degumming strains were obtained as follows:1) Aspergillus niger A: the temperature at 32℃, pH at 3, the medium volume was 50mL,and the seed volume was 5%.2) Aspergillus niger B: the temperature at 32℃, pH at 3, the medium volume was 50mL, and the seed volume was 5%.3) A1: the temperature at 30℃, pH at 7, the medium volume was 50mL, and the seed volume was 8%.4) A2: the temperature at 32℃, pH at 3, the medium volume was 50mL, and the seed volume was 5%.5) A3: the temperature at 26℃, pH at 4, the medium volume was 30mL, and the seed volume was 10%.③T he working condition of the degumming strainsThe appropriate components of the hemicellulase-producing medium of the Aspergillus niger B were consisted of 2.1% kojak, 0.9% NaNO3, 10g/L CaCl2, 1g/L KH2PO4, 1 g/L Na2HPO4, 1 g/L MgSO4.7H2O.The activity of mannanase and xylanase which produced by the Aspergillus niger B reached the peak value at 96 hour and 72 hour respectively. The activity of pectinase which produced by the Aspergillus niger A reached the peak value at 72 hour.The optimum working conditions of the degumming strains were obtained as follows:1) Aspergillus niger A: the temperature at 35℃, pH at 3.0, ramie (/g): enzyme solution (/mL) =1:30, the rate of the degumming was 32.59879% in this condition;2) Aspergillus niger B: the temperature at 35℃, pH at 3.0, ramie (/g): enzyme solution (/mL) =1:30, the rate of the degumming was 27.77764% in this condition;3) A1: the temperature at 35℃, pH at 7.0, ramie (/g): enzyme solution (/mL) =1:30, the rate of the degumming was 21.28403% in this condition;4) A2: the temperature at 35℃, pH at 3.0, ramie (/g): enzyme solution (/mL) =1:30, the rate of the degumming was 25.41377% in this condition;5) A3: the temperature at 23℃, pH at 3.0, ramie (/g): enzyme solution (/mL) =1:10, the rate of the degumming was 14.52581% in this condition..④Union-degumming of the degumming strainsAfter the ramie bast fiber was degummed by two kinds of the strains, the rate of the degumming reached 33.02% which was higher than the single strain.
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